Method for making abrasive tools

ABSTRACT

THE INVENTION RELATES OT A METHOD OF MAKING ABRASIVE TOOLS WHICH IS CHARACTERIZED IN THAT THE SPACES OF THE BLANK FILLED WITH ABRASIVE FILLER ARE TIGHTLY CLOSED AND THE BLANK IS PLACED INTO A CHAMBER WITH A SHAPING HOLE AFTER WHICH SAID CHAMBER IS FILLED WITH A FLUID MEDIUM, AND A PRESSURE IS BUILT UP IN SAID MEDIUM FOR EXTRUDING THE BLANK THROUGH THE SHAPING HOLE.

P 1972 L. F. VERESCHAGIN ET 3:;594'177 METHOD FOR MAKING ABRASIVE TOOLS Filed May 1, 1970 United States Patent METHOD FOR MAKING ABRASIVE TOOLS Leonid Fedorovich Vereschagin, Kutuzovsky prospekt 2/1, kv. 231; Evgeny Nikolaevich Yakovlev, Rusakovskaya ulitsa 4, kv. 63; Jury Sergeevich Konyaev, ulitsa Fersmana 11, kv. 26; and Evgeny Valentinovich Polyalrov, Belyaevo-Bogorodskoe 46, kvartal 39, kv. 73, all of Moscow, U.S.S.R.; Albert Pavlovich Novikov, Podolsky raion, p/o Akademgorodok, ulitsa Tsentralnaya 10, kv. 59, Moskovskaya Oblast, U.S.S.R.; and Valentin Nikolaevich Baku], ulitsa Kirova 34-a, kv. 12; Gely Fomich Skripko, ulitsa Vishgorodskaya 33, kv. 13; and Nekhemian Veuiaminovich Tsypin, ulitsa Dorogozhitskaya 26, kv. 59, all of Kiev, U.S.S.R.

Filed May 1, 1970, Ser. No. 33,738 Int. Cl. B24d 3/00 US. Cl. 51-293 2 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a method of making abrasive tools which is characterized in that the spaces of the blank filled with abrasive filler are tightly closed and the blank is placed into a chamber with a shaping hole after which said chamber is filled with a fluid medium, and a pressure is built up in said medium for extruding the blank through the shaping hole.

The present invention relates to the tool-manufacturing industry and more specifically it relates to the methods of making abrasive tools.

The method according to the invention will be used most successfully in making abrasive tools from superhard abrasives, such as diamond 0r cubical boron nitride or from hard-to-deform materials such as molybdenum, tungsten, etc.

Known in the art is a method of shaping abrasive bars for making abrasive tools consisting in that the blank made up of a malleable shell with a bar inside which is preliminarily coated with an abrasive filler, is deformed by elongation i.e. by reducing considerably the crosssectional area of the blank. After the deformation, the malleable shell is removed for uncovering the bar impregnated with the abrasive filler.

While using the above described method for elongating the blank by reducing its cross-sectional area, this is done by mechanical drawing or extrusion through a shaping hole. It is known that these processes fail to ensure the application of uniform pressure to the entire surface of the blank whereas the tensile stresses originated in the blank metal during these processes lead to failure of the blank if it is made of brittle and hard-to-deform metals such as molybdenum, tungsten, etc.

Besides, the above described method cannot produce the final shape of a tool in the cycle (or pass).

An object of the present invention resides in eliminating the aforesaid disadvantages.

The main object of the invention is to provide a method of making abrasive tools wherein the blank would be deformed under a uniform high pressure applied to the entire surface of said blank.

This object is accomplished by providing a method of making abrasive tools in which the spaces in the blank are filled with an abrasive material and said blank is deformed by extruding it through a shaping hole after which part of the blank is removed for uncovering the abrasive material wherein, according to the invention, the spaces of the blank filled with the abrasive material are tightly sealed and the blank is placed into a chamber provided with a shaping is built up in this medium for deforming the blank by extruding it through said shaping hole.

Patented Sept. 26, 1972 Such extrusion of the blank by the fluid medium kept under high pressure ensures the application of uniform pressure almost to the entire surface of the blank which increases the plasticity of the material and makes it possible to deform any brittle materials such as tungsten, molybdenum, etc.

:It is practicable that extrusion of the blank by the fluid medium under pressure be carried out with the blank heated above 300 C.

Extrusion at temperatures above 300 C. improves the adhesion of the abrasive filler to the material of the blank.

The method of making abrasive tools realized in compliance with the present invention allows the production in one pass of abrasive tools of any size and shape, for example, diamond sticks, tools for grinding small holes, tubular abrasize drills, etc., from any material including the hard-to-deform ones.

Given below is a detailed description of an embodiment of the present invention with reference to the accompanying drawings in which:

FIG. 1 shows a blank for making a diamond stick;

FIG. 2 is a section taken along line lI-II of FIG. 1;

FIG. 3 shows a blank for making hole-grinding tools;

FIG. 4 is a section taken along line IV-IV of FIG. 3;

FIG. 5 a blank for an abrasive drill;

FIG. 6 is a section taken along line VI-VI of FIG. 5;

FIG. 7 is a schematic representation of a blank deforming chamber according to the invention;

FIG. 8 shows an abrasive drill made in accordance with the invention.

The blank 1 (FIGS. 1 through 6) for abrasive tools is a metallic or ceramic body with internal spaces, filled with an abrasive filler. The shape and location of said spaces in the body of the blank 1 depend on the contemplated application of the tool.

For example, the blank 1 for a diamond stick is a metallic cylinder 2 (FIGS. 1, 2) with internal spaces in the form of channels 3; the blank for a hole-grinding tool is a cylinder 4 (FIGS. 3, 4) with channels 5 made longitudinally at its periphery. The cylinder 4 is inserted into a holder 6; the blank for an abrasive drill consists of a few coaxial cylinders 7 (FIGS. 5, 6), 8 and 9. These cylinders are arranged so that there are circular spaces 10 formed between them.

The channels 3, 5 and the circular spaces 10 of the corresponding blanks are filled with an abrasive filler consisting either of abrasive grains, e.g. diamond, cubic boron nitride, or of a mixture of abrasive grains with some powdered material (whether organic, metallic, or ceramic).

To produce a tool with the abrasive filler uniformly distributed over the cross-sectional area of the blank 1 and to hold more securely the abrasive grains in the material of said blank 1, it is recommended to compact the abrasive filler preliminarily.

This compaction may be carried out in a press or on a vibratory stand.

The blank 1 filled with abrasive filler is then deformed by extrusion in the course of which it is elongated by reducing its cross-sectional area.

For deforming the blank 1, the latter is placed into a chamber 11 (FIG. 7) provided with a hole 12. Located above this hole in the chamber 11 is a part 13 with a shaping hole 14.

The blank 1 is placed on this part above the shaping hole 14 for which purpose the blank 1 is provided with a tapered surface at the end.

The chamber 11 is filled with a fluid medium through a hole 15- Then a high-pressure generator (not shown) builds up a high pressure in said fluid medium.

To isolate the abrasive filler contained in the blank spaces from the fluid medium, said spaces are tightly closed with a plug 16 (FIGS. 1, 3, before placing the blank into the chamber 11.

Being placed into the chamber 11 (FIG. 7), the blank 1 is surrounded on the sides and from one face end by the fluid medium under pressure and is subjected to a uniform and all-round pressure of this medium; This increases the plasticity of the material of the blank 1 and the blank is extruded by the fluid medium through the shaping hole 14 of the part 13.

The fluid medium is constituted by liquids which do not freeze at the pressures used for extrusion.

The fluid medium may also be constituted by gases or by molten salts and low-melting metals.

The pressure build up in the fluid medium contained in the chamber 11 depends on the material of the blank 1 and the ratio of the diameter of the blank 1 to that of the shaping hole 14. The pressure grows with the strength of the blank material and with the increase in the ratio of said diameters.

For instance, for extruding a blank made of copper for which the ratio of the blank diameter to the diameter of the shaping hole is 4, the fluid medium pressure is taken to the range from 5000 to 6000 kg./cm., approximately.

For extruding a blank with the same ratio of diameters but made of molybdenum the fluid pressure should range from 16,000 to 17,000 kg./cm.

If the part 13 installed in the chamber 11 has a shaping hole 14 of a round, rectangular, etc. profile, this makes it possible to produce abrasive tools of the corresponding profiles, and, consequently, of various applications.

The abrasive filler is secured reliably in the blank 1 by deforming the latter with a sufliciently large elongation.

For still better fixing of the abrasive filler in the blank, the latter should be extruded by the fluid under pressure at the temperature of the blank above 300 C. The blank 1 is heated directly in the chamber 11 filled with the fluid medium, using any one of the known methods of heating.

If the abrasive filler consists of a mixture of abrasive grains with a powdered material, i.e. a low-melting metal, say, tin, the blank should be heated to 300-400 C.

If the powdered material consists of molybdenum powder, the blank heating temperature reaches 10001100 C. This temperature which exceeds the decomposition temperature of abrasive, for example, diamond, at normal pressure, can be used because the decomposition temperature of abrasive rises at a high pressure directly proportional to the rise of pressure. When the blank is heated above 400 C., inert gases, e.g. argon, are used for the fluid medium.

After the blank has been extruded, a part of it is removed for uncovering the abrasive material and thus producing an abrasive tool.

For example, a tubular abrasive drill 17 (FIG. 8) is manufactured from an extruded blank 1 (FIGS. 5, 6) as follows: first the plug 16 is cut off then the outer layer of the cylinder 7 is removed along the axis for uncovering the abrasive material; then a central through channel is formed by removing the cylinder 9 and drilling out the central hole 18 (FIG. 18) in the cylinder 7.

After these operations related to removal of a part of the blank, a tubular abrasive drill is obtained (see FIG. 8).

We claim:

1. A method of making abrasive tools comprising; providing a metal blank selected from the groups comprising copper, iron, molybdenum, tungsten and tin, said blank having at least one hollow interior space, filling said space with an abrasive filler material selected from the group comprising diamond, cubic boron nitride, a mixture of diamond with a metal powder, and a mixture of cubic boron nitride with a metal powder, sealing said abrasive filler-containing space from the exterior of said metal blank, positioning said filled blank in a closed chamber having an extrusion aperture, filling said chamber with a fluid medium, generating a pressure of up to 17,000 kg./ cm. in said chamber so as to extrude said blank through said aperture to thereby deform said blank to a predetermined external configuration, and removing a portion of said blank exterior to expose said abrasive filler material to thereby provide an abrasive tool.

2. A method as claimed in claim 1, wherein the blank is extruded through said aperture by said fluid medium under pressure at a blank temperature of from 300 C. to 1100 C.

References Cited UNITED STATES PATENTS 2,068,848 1/1937 Debats 51-309 3,249,410 5/1966 Lorenzo et a1. 51-309 2,170,164 8/1939 Stone 51-309 DONALD J. ARNOLD, Primary Examiner U.S. Cl. X.R. 51-3 09 

